The British government has demanded The Guardian destroy copies of material leaked by Edward Snowden.

theguardian.co.uk

The United States' National Security Agency (NSA) has secretly developed the ability to break common internet encryption, according to media reports citing documents from ex-NSA contractor Edward Snowden.

The Guardian, The New York Times and ProPublica reported the US intelligence agency used a variety of means of setting encryption standards.

They are said to range from the insertion of "back doors" in popular tech products and services, to supercomputers, secret court orders and the manipulation of international processes.

The publications said the NSA and its British partner Government Communications Headquarters (GCHQ) reported making strides against Secure Sockets Layer technology.

SSL protects millions of websites beginning in "Https" as well as virtual private networks, which are common for remote office workers and for people seeking to obscure their locations.

US intelligence officials made no immediate comment on the stories.

The Times and ProPublica cited an intelligence document saying the NSA spends more than $274 million a year on its "Sigint Enabling Project," which "actively engages the US and foreign IT industries to covertly influence or overtly leverage their commercial products' designs" to make them "exploitable".

New York Times removed specific facts after request

It is unclear from the articles how often technology companies voluntarily agreed to allow covert access to their offerings through back doors and how often the NSA compelled them to do so through secret court orders.

The New York Times and ProPublica said they were asked not to publish their findings by intelligence officials who argued their foreign targets might switch to newer forms of encryption or communications if the NSA tactics were revealed.

"Some specific facts" were removed, the New York Times said. The articles do not say which mainstream encryption systems have been effectively broken.

Previous disclosures by Snowden included an order from the Foreign Intelligence Surveillance Court, which meets in secret, compelling phone company Verizon Communications Inc to turn over all records showing which US numbers called which.

Thursday's stories are the first to be produced by the three-way partnership struck after the British government threatened The Guardian with legal action unless it destroyed copies of materials leaked by Snowden.

The Guardian did destroy computers in London containing the material but advised senior UK officials that copies had been sent to media outside Britain.